Pile driver mandrel



Nov. 7, 1961 F. RuscH PILE DRIVER MANDREL 3 Sheets-Sheet 1 Filed March 12. 1956 IN VEN TOR. F REM/c Ruse/4's 47' OPNEVS Nov. 7, 1961 F. RUSCHE 3,007,318

FILE DRIVER MANDREL Filed March 12. 1956 3 Sheets-Sheet2 Y N N IN V EN TOR.

F DR/C Fuse/1's w MZ M United The present invention relates to improvements in an expansible mandrel to internally engage and hold an elongated tubular shell in which concrete is to be cast in forming a pile, as blows are transmitted through the mandrel to the shell in forcing the latter into the earth. More particularly, the improvements relate to a mandrel which is expanded by pneumatic pressure, as distinguished from more commonly employed, mechanically expanded and contracted mandrel or core constructions.

It is an object of the invention to provide a pneumatically expanded mandrel which comprises a pair of like, generally cylindrical, rigid metallic mandrel sections or wings, which are of relatively great length, in relation to the length of the ultimately driven pile shell and pile, and which are provided with transverse, longitudinally spaced ribbing formations on the exterior, curved, pile engaging faces thereof to positively grip corresponding corrugations of the pile, so that a very well distributed and effective holding action is exerted on the pile shell throughout a considerable portion of its length.

Another object of the invention is to provide an expansible mandrel of the sort referred to in the preceding paragraph, in which a plurality of individual, pneumatically expansible envelopes or bladders of relatively short axial length are arranged along the entire length of the elongated mandrel sections. In accordance with the invention, each envelope is an individually sealed one provided with its individual air tube for inflation and deflation, so that if one envelope is damaged it can readily be isolated and capped off, and the mandrel thus kept in service.

It is another object of the invention to provide a pneumatically controlled mandrel in which the individually inflatable and collapsible expanding envelopes are of large external area, capable of collectively exerting tremendous outward force on the associated mandrel sections. When expanded, the sections engage the pile shell corrugations with great force to prevent its rotation when driven. Such relative rotation has in the past caused the mandrel to drive the bottom boot plate off the shell and ruin the pile. One of these sections is equipped with a longitudinally extending air manifold ported at intervals along its length to air chambers in the section, into each of which one or more air fittings for one of the expansible envelopes or bladders communicates. The fittings are releasably held in place, and the inflatable envelope is otherwise unattached to the manifolded mandrel section. Thus assembled, the individual envelopes are collectively inflated through their chambers and the common air manifold and are similar collapsed by appropriate valving connecting the manifold to a pressure source. Easily destructible air hoses, hose fittings, clamps, etc. are eliminated, and repair time is saved. It is apparent that removal, inspection and replacement of the envelopes or bladders is thus made very simple.

A still further and more specific object of the invention is to provide a mandrel construction in which opposed, pneumatically inflated mandrel sections as described are resiliently urged toward retracted or collapsed position by prestressed springs, yet are mechanically restrained and limited as to the degree of collapse and expansion. The mandrel structure is thus a rigid one in both inflated and deflated condition. Destructive wear and pinching of the expanding envelopes is greatly reduced in this way.

Patented Nov. 7, 1961 Specifically, oppositely acting coil springs act between the respective mandrel sections and shouldered stop studs to resist expanding movement of the sections and tend to collapse the same, while rigid spacers are secured on the face of one of the sections to be engaged by the other when the two sections are predeterminedly collapsed.

It is a still further object, in accordance with a related aspect of the invention, to provide an improved expansible pile driving mandrel of the general character described above, in which novel provisions are incorporated to insure the freeing of the expansible mandrel sections from the interior of the corrugated pile shell driven thereby. Specifically, the provision in question comprises an elongated, resiliently inflatable and stretchable hose which is wound lengthwise about the relatively movable expanding sections, between longitudinally spaced driving shoulders or corrugations on these sections. Upon completion of the driving operation, and release of the mandrel sections to permit their collapse, the hose is inflated to exert radial outward force upon the inner wall of the driven shell, the reaction of which force displaces the section inwardly toward one another to clear the pile corrugations.

The foregoing as well as other objects of the invention will become more apparent as this description proceeds, especially in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary view, partially broken away at longitudinal intervals, illustrating a pneumatically expansible mandrel in acocrdance with the invention, which is to be employed in the driving of elongated pile shells of the character shown in FIG. 7;

FIG. 2 is a view in transverse horizontal section along line 22 of FIG. 1, the mandrel sections being shown in their collapsed condition;

FIG. 3 is a view in section similar to FIG. 2, but showing the mandrel in an operative, expanded condition to engagethe pile shell;

FIG. 4 is a view in transverse horizontal section along line 4-4 of FIG. 1;

FIG. 5 is a fragmentary view in vertical section along line 55 of FIG. 4;

FIG. 6 illustrates one of the individual inflatable envelopes or bladders incorporated in the improved mandrel, as viewed from the direction in which it exerts mandrel expanding force; and

FIG. 7 is a more or less schematic elevational view of a mandrel in accordance with a modified adaptation and'extension of the principles of the invention.

As illustrated in FIG. 1 of the drawings, the mandrel of the invention, generally designated 10, will be understood to incorporate a driving head at its top and a driving base at its bottom, which may be of the character conventionally shown in FIG. 7, being designated 11, 12, respectively, for the impact driving of an elongated pile shell 13 of thin-walled construction. The provisions in this respect do not constitute part of the invention, though they will preferably include appropriate means associated with the head 11 to insure proper distribution of a hammer impact on the head 11 to the relatively expansible sections of the mandrel of the invention, illustrated particularly in FIGS. 2, 3 and 4 and generally designated by the reference numerals 14 and 15. As hereinafter more fully described, the sections 14, 15 have external,

longitudinally spaced driving ribs or shoulders which engage the corrugations of the thin shell 13 upon expansion of the sections, thus to grip the shell internally and transmit longitudinal or axial driving impacts to the latter without imposing a destructive stress on the shell 13. The grip on the shell prevents its rotation.

As herein illustrated, the mandrel 10 includes two of the sections 14, 15 which are generally similar and are of b approximately semi-cylindrical cross sectional outline. Each section is, in the main, made up of an elongated rolled steel beam of T-shaped cross section, the T-beam being of the order of, say, 40 feet in length and presenting a very rigid inner face plate 17 extending substantially the entire diametral width of sections 14, 15, and an integral radial web or flange 18 extending outwardly from the mid-point of the plate 17.

Each of the elongated T-beams has rigidly associated therewith an outwardly convex shell engaging wing plate 19 which is coextensive in axial length with the T-beam. The members 19 are preferably cut longitudinally from a cylindrical tube of substantial radial thickness, being somewhat less than semi-cylindrical in their arcuate extent. The ends of these out sections are given a beveled relief at 23 and are welded along their entire axial length to adjacent rear surfaces of the inner T-bearn cross plates 17, as indicated at 21. Similarly, the integral radial webs 18 of the T-beams 14, 15 are integrally united by welding at 22 to the longitudinal mid zone of the arcuate shell engaging wing plates 19. An extremely strong and rigid mandrel section is thus constituted.

The cross plates 17 of each of the mandrel sections 14, 15 are drilled through at opposed aligned points to provide pairs of opposed guide apertures 23 which, as illustrated in FIGS. 2 and 3, are spaced longitudinally from one another at intervals of, say, 4 ft., along a 40 ft. mandrel length. In a typical structure of this size there will be nine sets of guide apertures 23 over a 36 ft. length. Individually aligned apertures each receive a transverse pin or stud 24 having enlarged stop provisions 25, 25 at its opposite ends, and coil compression springs 27 act between the rear surfaces of the respective T-beam cross plates 17 and the head portions 25, 26, respectively, to urge the sections 14:, 15 toward one another. Relative movement of the sections in this direction is limited by longitudinally extending stop blocks 28 welded along opposite edges of one of the cross plates 17.

The mandrel is shown in FIG. 2, in its fully collapsed position; and in its fully expanded position in FIG. 3, in which the coil springs 27 are fully compressed, their coils engaging to prevent further expansion of the sections 14, 15.

The mandrel is expanded to the condition last described by a plurality of individual, resilient and pneumatically inflatable envelopes or bladders 29, there being in a typical mandrel as mentioned above a bladder 29 be tween each successive set of the guide studs 24 and plate guide apertures 23. These bladders are expanded and collapsed by provisions to be described.

As illustrated in FIG. 6, considered in conjunction with FIGS. 2, 3 and 4, and as indicated by dotted line in FIG. 1, the individual bladders 29 are of bellows shaped cross section and of somewhat elongated rectangular outline. For example, each bladder may measure 8 inches by 24 inches overall in its fully collapsed, flat condition. The bladder is, of course, sealed air tight at its ends and along its sides, and is preferably fabricated of rubber or synthetic rubber. One of the side walls thereof is equipped with a pair of longitudinally and laterally staggered tubular air couplings or fittings 30 of the general sort commonly applied to automotive inner tubes, by means of which the bladder is mounted to one of the mandrel sections, here indicated as the section 15. Other than at these connections, the individual bladders 29 are free to move and adjust themselves in relation to the adjacent inner surfaces of the mandrel T-beam cross plates 17. The fittings 30 are so located in relation to the bladder wall that the latter may be reversibly applied to one of the mandrel sections in the manner to be described.

The mandrel sections 14, are specially devised for the reception and servicing of the guiding and spring collapsing provisions, as well as the provisions to inflate the bladders 29, in the following fashion. As illustrated in FIGS. 2, 3 and 4, each of the arcuate wing plates 19 is provided with a pair of service or access holes in axial alignment with the guide apertures 23, and tubular sleeves 33 are secured in these apertures, extending inwardly to the cross plates 17, where they are laterally confined by annular rings 34 Welded to the plates 17. The outer extremities of the sleeves 33 may be welded to the arcuate wing plates 19, being of course shaped flush with the adjacent outer surface of those plates.

The mandrel section 15 is provided with a full length manifold housing, consisting of an elongated angle iron 35 having its flange extremities welded to the adjacent outer surface of the plate 17, and to one surface of the radial web 18, as indicated at 36. Referring to FIGS. 4 and 5, the manifold or elongated duct 35 thus constituted communicates through ports 37 at spaced points along its length, with individual sealed air housing 38 for the several bladders or envelopes 29. These are arranged as illustrated in FIG. 1, and may be constituted by individual lengths of channel section 39 (FIG. 5) welded to the side wall of manifold 35 and sealed at their ends by Welded end plates. The bladder stem 30 extends through appropriate bushing means 41 in the cross plate 17 of mandrel section 15, and is secured within its individual housing 38 by an appropriate sealing washer 42 and a manually releasable clamp nut 43 and lock nut 44. An access opening in each housing 38 is normally closed by a plug 45 and the arcuate mandrel plate 19 of the section is provided with a plurality of access openings 46 in alignment with these individual plugs, through which a tool may be inserted to release the nuts 43, 44 when it is desired to remove an individual bladder 29 for inspection, repair or replacement.

In the operation of removal, the mandrel is first fully expanded to the position shown in FIG. 3, and is then mechanically blocked open in that position, after which a damaged and deflated bladder is released in the manner just indicated. It is then manually withdrawn radially through the relatively wide space between the blocked apart mandrel members, without appreciable opposition to its movement, as by the studs 24 above and beneath the envelope or bladder, the spacing blocks 28, etc. A replacement bladder is reinserted and connected with equal speed and facility, the operation consuming less than a minutes time. This is a great advantage attaching to the use of individually inflatable envelopes, bladders or like members, with individual pressure connections to the air manifold 35, by which the inflatable members are supplied with air independently of one another.

Such removal does not disable the mandrel as a whole from use, the remaining individual bladders 29, when inflated, afford ample expanding force to hold the pile shell under any usual driving impact.

If desired, the section 15 may be equipped with a further set of bladder porting provisions, similar to those described above and generally designated 48. The fitting 30 of this set is closed by a manually releasable cap nut 49, to which access may be had from another opening 50 in the arcuate plate 19 of that section.

The longitudinally extending air distributor duct or manifold 35 will be appropriately sealed off at its lower end, and will at its opposite upper end be appropriately connected to a source of air pressure, as through a threeway valve (not shown), which will enable air to be admitted to the manifold, individual air housings and bladders 29 to inflate the same, to be held under pressure as the mandrel-is driven, and to release the pressure after driving. I

It is believed that the use of the improved mandrel is obvious from the foregoing description. An elongated shell 13 is telescoped thereover when the mandrel 10 is collapsed, i.e., in the positions shown in FIGS. 2 and 4, whereupon the sections 14, 15 are pneumatically expanded, as shown in FIG. 3, to cause their axially spaced driving shoulders 52 to take expansive gripping engagement with the corrugations of the shell 13. After driving, pneumatic pressure is released and the springs 27 return the sections 14, 15 to the collapsed position of FIGS. 2 and 4, whereupon the mandrel is lifted from the shell.

in a typical installation and use a pressure of about 50 pounds per square inch is applied to the bladders 29 during driving. The springs 27 are placed under an initial compression of, say, 100 pounds, being fully compressed as in FIG. 3 by the pneumatic force of the bladders 29 to act as positive stops opposing further expansion of the sections. The bladders will be located about 4 ft. apart along the overall mandrel length.

FIG. 7 of the drawings illustrates somewhat schematically a modified mandrel arrangement, in which expanding and contracting provisions may be considered to be similar to what is shown in the remaining figures. in the alternative, the provisions in question may be applied to other types of expansible mandrel, since they deal primarily with means for insuring that the driving ribs or shoulder corrugations 52 shall be disengaged from the corrugations of the pile shell, specially designated 53.

As shown in FIG. 7, one of the mandrel sections 14, 15 is equipped with a hose connection 54, which may be associated through its own control valve with the valving which governs expansion and contraction of the sections 14, :15 of an installation like that previously described. An elongated, resiliently stretchable and inflatable hose 56 is coupled to the connection and is brought in spirals down around the sections 14, 15, for example in the space between successive passes of the corrugated rib or driving shoulder formations 52. The lower end of the hose 56 is sealed and is appropriately secured adjacent the lower end of the mandrel.

The inflatable hose 56 is employed only after the driving phase has been completed and it is desired to free the mandrel from the driven shell 13. At such time, the hose 56 is pressurized through the connection 54, cansing it to inflate and bear against the inner Wall of the shell. The inward reactive force thus set is effective to urge the sections 14, 15 radially inwardly, disengaging the driving shoulders from the shell corrugations 53. Further contraction of the sections may be produced by contracting or retracting springs or the like, whereupon the mandrel unit is lifted out of the shell.

It is fully realized that because this type mandrel expands in only two directions the mandrel in its expanded position would, theoretically, have only two points of contact in any plane normal to the long axis of the pile. This condition gives a minimum of contact area between the mandrel and the shell being driven, and in easy driving this should prove suflicient.

However, if the mandrel exhibits a tendency to slip in relation to the shell during driving operations, one may weld on to the periphery of the mandrel, between the drive shoulders, wedge shaped pieces 58 which I choose to call compensating wedges. These wedges are so shaped to give the periphery of the mandrel a radius equal to the inside radius of the shell being driven over a large area of the mandrel face. This will increase the contact area between the mandrel and the shell and hence increase the total friction to eliminate slippage.

The compensating wedges 58 and other contact areas of the mandrel may also be covered with an abrasive facing of a suitable nature which will increase the coefficient of friction between the mandrel and the shell when the mandrel is expanded and this likewise will insure against slippage.

What I claim as my invention is:

1. An expansible mandrel for driving pile shells and the like, comprising a pair of opposed elongated mandrel members of extensive overall length approximating that of a shell to be driven and generally semicircular cross section, having curved, longitudinally continuous outer surfaces for gripping engagement with the pile shell upon expansion of the mandrel, said mandrel members having .mutually facing inner surfaces of substantial width ap proximating the diametral dimension of the mandrel member, with a space between said mandrel members opening radially to the exterior of the mandrel, means located at spaced points along the length of said mandrel members for holding the same together, and fluid pressure expanding means for said mandrel members, comprising a longitudinal series of individually inflatable members removably secured between and spaced along said mandrel members in zones between said respective holding means, said inflatable members being engageable when inflated with said inner surfaces over substantially the entire width of the latter, and means to individually inflate said members, comprising an elongated manifold element extending longitudinally of said mandrel members and located within the outer peripheral limit of said mandrel, said manifold element having individual pressure connections supplying a plurality of said inflatable members independently of one another, said mandrel members being separable from one another sufficiently to permit ready radial removal of collapsed inflatable members from said space from between said mandrel members, without effective opposition by said holding means.

2. An expansible mandrel for driving pile shells and the like, comprising a pair of opposed elongated mandrel members of generally semi-circular cross section having curved outer surfaces for gripping engagement with the pile shell upon expansion of the mandrel, said mandrel members having mutually facing inner surfaces of sub stantial width approximating the diametral dimension of the mandrel member, with a space between said mandrel members opening radially to the exterior of the mandrel, means located at spaced points along the length of said mandrel members for holding the same together, and fluid pressure expanding means for said mandrel members comprising a longitudinal series of individually inflatable members removably secured between and spaced along said mandrel members in zones between said re spective holding means, said inflatable members being engageable when inflated with said inner surfaces over substantially the entire width of the latter, and means to individually inflate said members, comprising an elongated manifold element extending longitudinally of said mandrel members and located within the outer peripheral limit of said mandrel, said manifold element having individual pressure connections supplying a plurality of said inflatable members independently of one another, said mandrel members being separable from one another sufficiently to permit ready radial removal of collapsed inflatable members from said space between said mandrel members, without efliective opposition by said holding means.

References Cited in the file of this patent UNITED STATES PATENTS 700,707 Raymond May 20, 1902 2,170,188 Cobi Aug. 22, 1939 2,313,625 Cobi Mar. 9, 1943 2,321,146 Jones June 8, 1943 2,625,015 Gobi Jan. 13, 1953 2,684,577 Smith July 27, 1954 2,741,093 Riker Apr. 10, 1956 FOREIGN PATENTS 728,211 Great Britain Apr. 13, 1955 

